Multiple stage sequential escapement mechanism



R. D. EMERY 3,487,700 MULTIPLE STAGE SEQUENTIAL ESCAPEMENT MECHANISM Jan. 6, 1970 NOZZLE Filed Jan. 23, 1968 ivALvE FIGJ INVENTOR ROBERT D. EMERY United States Patent US. Cl. 74-352 7 Claims ABSTRACT OF THE DISCLOSURE A set-stop counter includes a control ring interconnected to position a valve and held in place by a spring an L- shaped lever one end of which selectively engages a pair of adjacent edge notches in the control ring. The lever is controlled by a pivotally mounted sear assembly which is releasably coupled to the latch member by a notch and lip connection. A trip member actuated .by a lowest unit counter wheel actuates the sear assembly which includes a pair of stacked sears pivotally attached to a pivot pin at one end.

The control ring includes a fully open notch of a selected depth and an immediately adjacent partial open notch of a lesser depth. The latch lever is pivotally mounted with a latch tooth in engagement with the first notch by proper rotation of the control ring to fully open the valve and with the opposite end including a depending lip inter-engaging a latching notch in the first sear member. The first sear is pivotally mounted on the pin with the outer end in the path of the trip member. The second sear is co-axially mounted with the first sear by a slotted connection mating with the pin and is spring loaded to space the outer end from the trip member. The second sear also includes a latching notch spaced from the corresponding notch of the first scar and therefor the lip of the latch lever. The first sear is pivoted by the trip member to release the latch lever whereupon the control ring rotates with the latching tooth moving from the first to the second notch, In so doing, the latching lip moves into the spaced notch of the second sear to establish a second latching of the latch lever and further moves the second sear from its initial position into a second position with the outer end now in the path of the trip member. As a result, the next movement of the trip member actuates the second sear, thereby releasing the second sear from the latch lever and allowing the control ring to move to the final limit position corresponding to a valve closed position.

This invention relates to a two-stage sequential escapement mechanism and particularly to such a mechanism for operating of a loaded member for controlling a setstop counter or the like.

In the controlled movement of a mechanical load means, it is often desirable to provide for sequential actuation. For example, in the marketing of petroleum products, metering of a dispensed product may more accurately be obtained by terminating flow in a stepped sequence. A counter may be interconnected to the meter and include means for presetting of the counter from a Zero or reference position. The counter is then driven in a reverse or subtractive manner from the preset position and when it reaches the reference or zero position, actuate a switch or mechanical latch to terminate flow. In order to obtain accurate recording and terminating of flow, it is desirable that the flow rate be reduced shortly prior to the zero reading. A co-pending application entitled Predetermining Counter Apparatus for Flow Control Systerns and the Like filed by Charles E. Freese and Robert D. Emery, May 24, 1967, Ser. No. 640,956, assigned to a common assignee with the present application discloses a highly satisfactory sequential means for closing of a valve in response to the operation of a set-stop counter.

As more fully disclosed in such application, the setstop counter includes a control ring interconnected to position a valve. The ring is held in place by a spring loaded lever which selectively engages a pair of adjacent edge notches in the control ring, The lever is controlled by a pivotally mounted sear which is releasably coupled to the latch member by a notch and lip connection. A trip member actuated by a lowest unit counter wheel pivots the sear to release the latch member. Just prior to the beginning of the last revolution, the wheel actuates the trip member and the latch member moves from the first or full flow notch to a partially open and reduced flow notch. The sear is mounted by a slot and pin connection such that the movement of the latch lever resets the sear as it moves into the second notch. The terminal portion of the final revolution again trips the latch member and the ring moves to the valve closed position. Consequently, rotation of the counter wheel provides a sequential stepped operation of the latch lever from one notch to the second notch and then finally to the outer periphery of the wheel thereby permitting the control ring and valve to move to the full stop position in steps. Although the above system provides very satisfactory means for controlling the valve mechanism, it does require somewhat careful construction of the several members to provide proper timed movement of the mechanism between the several notches.

The present invention is particularly directed to such an escapement mechanism having a positive controlled stepped movement. Generally in accordance with the present invention, a pair a scar members are movably mounted adjacent a latch member and adapted to be actuated by a trip unit. the latch lever releasably engages a control member connected to a load which is adapted to be actuated in sequential steps between a first position and second position. In a first position, the latch is operatively disengaged from the sear member. When the load member is moved to the second position, a first releasable latching engagement is made with the latch lever which automatically eifects a latching engagement between the latch lever and a first sear member. The second sear member is mounted and constructed to lie in the path of the latch lever when the first sear is tripped to release the latch lever and the load member which then moves a first step and also moves the latch lever into a second releasable latching engagement With the second sear member and also moves the second sear member into position to be actuated by the trip unit. Consequently, the next movement of the trip unit releases the latch lever which allows the load member to move to the first or starting position.

In a preferred construction, as applied to the setstop counter for the controlled closing of a valve between a fully opened and a fully closed position, a control ring includes a fully open notch of a selected depth and an immediately adjacent partial open notch of a lesser depth. The latch lever is pivotally mounted with a latch end or tooth in engagement with the first notch by proper rotation of control ring to fully open the valve and with the opposite end including an arm or lip inter-engaging a latching notch in the first sear member. The first sear member is pivotally mounted with the outer end in the path of a trip member. The second sear is co-axially mounted with the first sear by a slotted connection and is spring loaded to space the outer end from the trip memher. The second sear also includes a latching notch spaced from the corresponding notch of the first sear and therefor the lip of the latch lever. When the first trip action is established, the first sear member pivots to release the latch lever whereupon the control ring rotates with the latching end tooth of the latch moving from the first to the second notch. In so doing, the latching lip moves into the spaced notch of the second sear to establish a second latching of the latch lever and further moves the second sear member from its initial position into a second position with the outer end now in the path of the trip member. As a result, the next movement of the trip member actuates the second sear member, thereby releasing the second sear member from the latch lever and allowing the control ring to move to the final limit position corresponding to a valve closed position.

Applicant has found that this provides a very positive and reliable sequential actuation of the load member or control ring.

The drawing furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description.

In the drawing:

FIG. 1 is a view of a counter and flow meter assembly with parts broken away to more clearly disclose the subject matter of the present invention;

FIG. 2 is a fragmentary side elevation view of the structure shown in FIG. 1, and taken generally along lines 22 of FIG. 1;

FIG. 3 is a top fragmentary view showing the rotating control ring and escapement mechanism in a partial fl w locking position; and

FIG. 4 is a view generally similar to FIG. 3 showing the control ring moved to the valve closed position.

Referring to the drawings and particularly to FIG. 1, the present invention is diagrammatically shown applied to a fiow control system which may be employed, for example, at a petroleum bulk loading plant or the like. Generally, the flow control system includes a presettable counter 1 interconnected to be driven from or by a meter 2 which is inserted in a flow line between a storage tank, not shown, and a dispensing nozzle 3. The meter 2 may be the usual volumetric flow type meter which produres a mechanical output in accordance with the volumetric fiow therethrough to drive the counter 1.

The presettable counter 1 includes a plurality of display or counting wheels 4, of which only one is shown. The wheels normally read in the decimal system to tenths or any other desired lowest unit. Referring to FIG. 2, a drive shaft 5 to the meter is interconnected through a coupling shaft 6 to the counter wheels which will generally be interconnected through a sequential coupling mechanism to provide cascaded actuation of the several wheels to count from a set number to Zero. An input shaft or rod 7 is provided for each of the display wheels 4 and permits presetting of the corresponding wheel from a zero reference position by reciprocation thereof; for example, as shown in the previously referred to co-pending application. This permits presetting of the counter 1 f r discharge of any predetermined amount of product within the limit of the counter 1. A tripper arm 8 is movably mounted above a cam 9 which is secured and rotates with the illustrated control count wheel 4. The cam 9 includes a triggering notch 10 which, as the wheel 4 rotates, engages and pulls the arm 8 to the left as viewed in FIG. 1. The arm 8 is held in spaced relation to cam 9 by the structure of the other wheel units and released for actuation by illustrated wheel 4 only during the final portions of the next to the last and the last revolutions. The trigger arm 8 is interconnected to an escapement unit 11, particularly forming the subject matter of the present invention, for controlling the movement and position of a valve control ring 12. The latter is interconnected to a control valve 13 in any suitable manner. A rod-like linkage is shown in FIG. 1 and a spring load of the ring 12 biases the valve to a closed position. The valve 13 is manually moved to the open position with the escapement unit 11 coupled to the valve ring 12 to hold the ring 12 and valve 13 in a full flow or a partial flow position as hereinafter described.

Generally, in the operation of the unit the preset-stop counter 1 is preset to a particular quantity to be discharged. The valve 13 is then manually opened with the valve ring 12 moving to a full open position and interlocked in such position by the escapement unit 11. The flow through the meter 2 results in a subtractive driving of the set-stop counter 1 toward the zero or reference position. When the other wheel higher than the illustrated count wheel 4 reaches a Zero position, the illustrated count wheel 4 becomes an effective control and just prior to completion of the next to the last revolution, the notch 10 engages the tripper arm 8 to actuate the escapement unit 11 and tripper the unit to a partial flow position. This allows the control ring 12 and valve 13 to move to a partial flow position. At the end of the final revolution of the count wheel 4, the tripper arm 8 is again pulled to actuate the escapement unit 11 and allows the control ring 12 and valve 13 to move to the fully closed position.

The precise construction of the presettable counter and its interconnection to a meter as well as the interconnection of the control ring 12 to a particular valve can be of any suitable or desired construction and consequently no further description thereof is given. The present invention is particularly directed to a novel escapement construction, a preferred construction of which is clearly shown in the drawing and described as follows.

The control ring 12 is rotatably mounted within the base portion of a housing 14 and is biased to rotate in a counterclockwise direction and thereby move valve 13 to the closed position. An L-shaped latch lever 15 is pivotally mounted to the base of the housing 13 with a latching end or tooth 16 riding on the outer peripheral edge 18 and is latched against pivotal outward movement the escapement unit 11 and is shown in FIG. 1 in engagernent with a first or leading notch 17 which terminates in a trailing camming edge 18. The latch tooth 16, in the position of FIG. 1, engages the trailing camming edge 18 and is latched agianst pivotal outward movement by the escapement unit 11 to hold the ring 12 and therefore, the interconnected valve 13 in a fully opened and full flow position. Immediately adjacent the trailing end of the camming edge 18, a second partial notch 19 is formed in ring 12 and is generally approximately onehalf the depth of the first notch 17 in the illustrated embodiment of the invention. The trailing end of notch 19 is similarly formed as inclined surface to define a cammmg surface for the latching tooth 16. The escapement unit 11 is sequentially actuated to first allow the latch lever 15 to pivot to dispose the latching tooth 16 in the notch 19 and hold the valve in a partial flow position shown in FIG. 3 and finally releases the latch lever 15 with the latching tooth 16 riding on the outermost periphery of the control ring 12 and the valve 13 in the fully closed position of FIG. 4.

More particularly, the L-shaped latch lever 15 is secured to a latch pivot pin 20 at the junction of its two arms or leg portions with the one leg extending towards the control ring 12 and terminating in the latching tooth 16. The opposite lever leg extends laterally at right angles to the first leg and terminates in its outer end in a depending interlock arm or lip 21. A first stage or step sear 22 and a second stage or step sear 23 are mounted in stacked relationship one above another beneath the second leg of the latch lever 15 with the depending lip 21 extending downwardly across the adjacent edges of both sears. The sears 22 and 23 are pivotally mounted on a pivot shaft or pin 24 to permit pivotal movement with respect to the lip 21 for selective releasable operative engagement and disengagement.

More particularly, the first step sear 22 is generally a plate like arm or member having a pivot hub 25 pivotally mounted on the outermost end of the pivot shaft or pin 24 in any suitable manner. A spring arm 26 extends laterally from the hub portion 25 to the right as viewed in FIG. 1, to lie in generally parallel spaced relation to the one leg of the latch lever 15. A spring 27 is secured at the one end to the arm 25 and at the opposite end to the latch lever 15 by similar aperture and hook connections 28a. The spring 27 provides a bias on the latch lever 15 tending to pivot it in a counterclockwise direction to resiliently hold the latching tooth 16 in sliding engagement with the peripheral edge of the control ring 12. The spring 27 also exerts a counterclockwise pivotal action on the first step sear 22 and urges the left edge thrust into engagement with the depending lip 21 of the latch lever 15. A notch in the corresponding edge of the sear 22 defines a locking ledge 28 which is engaged by the lip 21 to permit the pivotal movement of the latch lever 15 in a clockwise direction as a result of the force of the spring loaded ring 12. The control ring 12 thus tends to rotate the latch lever 15 in a clockwise direction. The interengagement of the latch lever lip 21 with the ledge 28, however, positively prevents said such movements. As a result, with the first sear 22 in the position of FIG. 1 and with the latch lever 15 engaging the first notch 17, the control ring 12 is held in the fully open position.

The outer end of the first sear 22 is provided with an offset portion defining a trip end portion 29 which lies in the path of a trip plate 30 such that movement of the latter to the right pivots the seat 22 and affects disengagement of the lip 21 from ledge 28, thereby permitting the latch lever 15 to pivot. The lip 21 moves over the outer edge of the sear 22 outwardly of ledge 28 and holds it in the tripped position and from the path of arm 8, as shown in FIG. 3.

The trip plate 30 is interconnected and forms a part of the tripper arm 8. In the illustrated embodiment of the invention, a crank 31 is rotatably mounted on the coupling shaft 6 and extends upwardly and downwardly therefrom, with the opposite ends pivotally interconnected respectively to the trip plate 30 and the arm 8. Suitable interconnecting springs bias the crank in a clockwise direction and hold the trip plate 30 spaced from the ends of the sear 22. When the arm 8 is pulled forwardly, the crank 31 pivots in a counterclockwise direction and causes the trip plate 30 to move rectilinearly to the right as viewed in FIG. 2. The plate 30 engages and forces the end portion 29 of sear 22 to the right to release the lever 15. Arm 8 is returned to the standby position to allow the escapement unit 11 to move the second sear 23 into operating position.

The second sear 23 is disposed between the base of the housing 14 and the first sear 22 generally in superimposed relationship therewith. The second sear includes a slot 32 through which the pivot pin 24 passes. A spring 33 is hooked to a lateral extension 34 of the second sear and is interconnected to a pin 35 on the base housing 14 and acts to continuously bias the second sear 23 in a counterclockwise direction as viewed in the drawings and to further cause the sear 23 to retract with the upper end of the slot 32 bearing on the pivot pin 24. The sear 23 generally is constructed to have a configuration similar to that of the first sear 22 and includes an outer trip end portion 36 which in the spring loaded retracted position is spaced from the path of the trip plate 30. The second sear 23 also includes a notch defining a locking ledge 37 in the periphery or edge adjacent the latch lip 21 of the latch lever 15. In the fully open position with the second sear 23 held in the retract position by the spring 33, as shown in FIG. 1, the ledge 37 is located outwardly of the latch lip 21 but in the pivotal path of such lip.

In operation, when the first sear 22 is pivoted to disengage lip 21, lever 15 is released and the rotation of the control ring 12 causes the latch lever 15 and particularly tooth 16 to ride up camming edge 18 and positive pivot the lever 15 in a counterclockwise direction. The pivotal movement of the latch lever 15 causes the latching tooth 16 to move into engegement with the second notch 19 and the lip 21 to move from the locking ledge 28 into engagement with the adjacent periphery of scar 22 to hold it in the pivoted position of FIG. 3 and into engagement with the locking ledge 37 in the second sear 23 upon release of trip member or plate 30. The final rotation of the latch lever 15 positively moves the second sear 23 against the force of spring 33 until the opposite end of the slot 32 engages the pivot pin 24, thereby positioning the trip end portion 36 of the second sear 23 in the path of the trip plate 30 which has returned to its normal position as a result of the return spring. The next movement of the tripper arm 8, as a result of the final revolution of the wheel 4, results in release movement of the trip plate 30 into engagement with the second sear 23. The second sear 23 pivots and disengages the latch lever lip 21 such that the lever 15 is free to rotate. The control ring 12 is thereby released and moves to the fully closed position shown in FIG. 4, with the lever 15 pivoted clockwise to locate the latching tooth 16 on the outer periphery of ring 12 and lip 21 moved outwardly of locking notch 37 in the second sear 23. Thus, the final two revolutions of the display wheel 4 establish a sequential movement of the control ring 12 to provide a decreased flow for one revolution and to then finally stop the flow by closing of the 'valve 13 completely.

The operation is briefly summarized as follows. Assuming the valve 13 is in the normally closed position with the escapement unit 11 as shown in FIG. 4, the valve 13 is manually or otherwise positively moved to the open position thereby rotating the control ring 12 in a clockwise direction. The latching tooth 16 of the latch lever 15 drops into the first notch 17 in the control ring 12 with the locking tooth 116 of the latch lever 15 engaging the tnailing or camming edge of the locking lip engaging the locking ledge 28 in the notch of the first se'ar 22. The spring 33 connected to the second sear 23 establishes counterclockwise rotation of such sear and also retraction thereof to locate the upper end of the slot 32 abutting the pivot pin 24. The outer or the trip end portion 29 of only the first sear 22 is therefore in the path of the trip plate 30. As the counter approaches the reference position, the terminal portion of the second to the last revolution of the display wheel 4 actu'ates the trip arm 8 and moves the trip plate 30 in the direction disengaging the first sear 22 from the latch lever 15. The load on the control ring 12 rotates the ring to close valve 13. The counterclockwise rotation of the ring 12 forces a clockwise rotation of the latch lever 15 with the latch lip 21 moving into engagement with the latch ledge 37 of the second sear 23 with the final movement moving the second sear into operative position with respect to plate 30. The next revolution of the wheel 4 again actuates the trip plate 30 to release the second sear 23 and permit the control ring 12 to further rotate in a counterclockwise direction thereby moving the valve .13 to a fully closed position.

The present invention has been found to provide a highly reliable control of a load member such as a control ring and particularly sequential controlled movement thereof without requiring close tolerances between the relative spring forces and the speed of the movement of the escapement components.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

Iclaim:

1. A multiple stage escapement mechanism for a movable member having means biasing the movable member to a selected position comprising a latch means movably mounted adjacent the movable member and releasably coupled thereto for holding the movable member in at least two positions difierent than said selected position, a plurality of latching elements adapted to be releasably coupled to said latch means and arranged and constructed to be sequentially disposed in releasable latching engagement therewith and including means coupled to and actuated by said latch means to successively move said latch elements into operative latching position with said latch means to sequentially hold said movable member against movement in said two positions.

2. A multiple stage escapement mechanism for a movable member having means biasing the movable member to a selected position comprising a latch means movably mounted adjacent the movable member and releasably coupled thereto for holding the movable member in at least two positions diiferent than said selected position, a plurality of sear members for establishing sequential stepped movement of the movable member and including a first sear member movably mounted adjacent said latch means, a releasable latching connection of said first sear member to said latch means in said second position preventing movement of said latch means, a trip means disposed to move said first sear member to open said releasable connection and permit movement of the latch means and said movable member, each successive sear member of said plurality of sear members being mounted for successive actuation by said trip means and each having a separate means for forming a releasable connection to said latch means, each of said successive sear members being movably mounted and resiliently biased to a first limit position, said latch means releasably engaging said separate means of successive sear members in response to each release from a sear member and moving and holding the next succeeding sear member in a second limit position, said trip member releasably engaging each of said successive sear members with the sear member in the second limit position.

3. The multiple stage escapement mechanism of claim 2 wherein said movable member is resiliently biased to a selected first portion and includes a plurality of adjacent locking notches, said latch means includes a latch lever pivotally mounted adjacent the movable member and having a latching tooth aligned with said notches, means biasing said latch lever to hold the latching tooth within said notches to hold the movable member in a second position, said sear members being pivotally mounted in stacked relation, said lever passing over said sear members and including a locking lip for engagement with a corresponding latch edge of said sear members to said lever, said successive sear members including pivot slots for individual movement between a first limit positions and a second limit position, resilient means bias the successive sears to said first limit position, each of said latch edges including a locking ledge for engagement with said locking lip with said ledges in successive sear members being spaced progressively further outwardly of the pivotal mount whereby said ledges are successively engaged by said lip, said lip releasable engaging said successive sear member in response to release of the preceding sear member and moving and holding each of said successive sear members in the second limit position, a trip member movable in a selected path to engage said first sear member to open said releasable connection and permit movement of the latch lever and said movable member, said trip member releasably engaging said successive sear members with the sear members in the second limit position.

4. The multiple stage escapement mechanism of claim 3 wherein each of said sear members includes a cam surface means immediately outwardly of the latching ledge, said cam surface means being engaged by said locking lip to hold the cam in a position set by the actuation of the trip member.

5. The multiple stage escapement mechanism of claim 2 wherein said movable member is a control ring, said latch means includes a latch lever pivotally mounted adjacent the control ring and releasably coupled thereto to hold the control ring in a second position, said first sear member being movably mounted adjacent said lever, a releasable connection of said first sear member to said lever, said means being a trip means disposed to engage said first sear member to open said releasable connection and permit movement of the latch lever and said control ring, said successive sear members including a second sear member mounted adjacent said lever, a second releasable connection for connecting said second sear member to said lever, said second sear member being movably mounted to move between a first limit position and a second limit position, a resilient means coupled to said sear member and urging the sear to said first limit position, said lever releasably engaging said second sear member in response to release of said first sear member and moving and holding said second sear member in the second limit position, said trip means releasably engaging said second sear member with the second sear member in the second limit position and disengaged in the first limit position, said trip means being movable to pivot said second sear member against said resilient means and releasing said lever and permitting second movement of the control ring in response to movement of the sear by said trip means.

6. The multiple stage escapement mechanism of claim 2 wherein said movable member includes a first notch and an immediately adjacent and following second notch of lesser depth in the outer peripheral edge and each notch having an inclined trailing edge, said latch means including a lever having a locking leg terminating in a locking tooth and a latching leg terminating in a depending arm, a pivotal mount connected to said lever and permitting pivoting with respect to said notches, means biasing the locking tooth into engagement with said outer peripheral edge and into said notches, each of said sear members being a plate-like member pivotally mounted in stacked relation on a common mounting pin with said lip extending laterally across the one edge of all said sear members, the second of said sears having a pivotal mounting slot portion mating with said pin, means urging said sears to pivot into engagement with said lip and to retract said second scar, and means forming a part of said lip and said sear means to establish releasable latching engagement between said lip and sear members with said means constructed and arranged to establish successive engagement between said first and second sear members upon successive operative movement of the trip member.

7. The multiple stage escapement mechanism of claim 2 wherein said movable member is a rotatable ring mounted on the interior bottom wall of a housing, said ring having a first notch and an immediately adjacent and following second notch of lesser depth in the outer peripheral surface and each notch having an inclined trailing edge, said latch means including a generally L- shaped member having a locking leg terminating in a locking tooth and a latching leg terminating in a depending lip, a pivotal mount connected to the junction of the legs and permitting pivoting with respect to said notches, means connected to said lever and biasing the locking tooth into engagement with said outer edge and into said notches, each of said sear members being a plate-like member pivotally mounted on a common mounting pin, the second of said sear members having a pivotal mounting slot portion mating with said pin, said sear members extending from said pin generally perpendicular to the latch lever, spring means urging said sear members to pivot into engagement with said lip and to retract said second sear member, said first sear member having an edge notch defining a latching ledge to receive said lip on the lever, said second sear having an edge notch 9 10 spaced outwardly of said first named edge notch to de- 3,057,553 10/1962 Billeter 235-132 fine a second latching ledge to said lip in response to 3,089,616 5/1963 Wilson 235-132 XR movement of said first sear from said lip, said latch lever 3,231,191 1/ 1966 Berck 235132 moving said second sear to the opposite end of the slot, 2,793,692 5/ 1957 Horstmann et a1.

and said trip member being reciprocally mounted with the one end aligned with the outer end of the first sear member and With the outer end of said second sear mem- FOREIGN PATENTS her in said second limit position and operable to pivot the sear members against the force of said spring means 823645 11/1959 Great Bntam' and thereby release the latch lever.

10 FRED C. MATTERN, J 11., Primary Examiner References Cited F. D. SHOEMAKER, Assistant Examiner UNITED STATES PATENTS l. 1,323,661 12/1919 Urton 74-534 Us c XR 2,904,251 9/1959 Hazard et al. 235-132 15 74527; 137-624'19,624-22;235-132 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION January 6, 1970 It is certified that error appears in the above-identified patent line 20, cancel "tripper" and substitute "trigger" line 42, cancel "portion" and substitute "position" line 53-54, cancel "positions" and substitute "position" mill 1:. scam. a! Commissioner of Patents Patent No. 3487'7OO Inventor(s) Robert mery and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 41, after "latch" insert (lever) Col. 4 Col. 7, Col. 7,

SIGNED AND SEALED JUL 2 1 1970 ISEAL Afloat:

EdwardMFletchn,I|-. Attcsling Offim FORM PC7-1050 (10-69) .3 Jug.

UscoMM-oc 003104 09 U S, GOVERNHINT 'IIIITIIIGRFHCI vlll'lll 

